In the tobacco industry, cigarette packing machines are known comprising an output wheel which rotates about a respective axis to feed a number of gripping heads along a folding path. Each gripping head is engaged by and retains a respective packet of cigarettes comprising two minor longitudinal lateral walls, each of which is defined by an outer longitudinal tab and an inner longitudinal tab superimposed and connected integrally to each other.
In known machines of the above type, each gripping head receives the relative packet with the relative outer longitudinal tabs in an open position, and comprises two folding wings, each of which is movable, at a folding station extending along a portion of the folding path, from an initial open position supporting the relative outer longitudinal tab in the open position, and a final closed position to fold the relative outer longitudinal tab into a closed position contacting the relative inner longitudinal tab.
In known machines of the above type, the movement of the folding wings into the final closed position has been found to compress the packets transversely, thus resulting, particularly when using thin blanks, in at least one of the major lateral walls of the packets bulging outwards.